The Destruction of WTC 7

(Background: at the end of 2008, NIST published the final official report on the destruction of WTC 7, the third skyscraper totally destroyed on 9/11. Discarding earlier official hypotheses (and based on no physical evidence, as "[N]o metallography could be carried out because no steel was recovered from WTC 7"), the institute claimed that ordinary office fires resulted in an "extraordinary event", the skyscraper's total symmetrical destruction, which progressed at complete freefall acceleration for over 2 seconds, or the span of 8 floors.)

To fully understanding the nuances in the 2008 Report by NIST, it might be helpful for people to learn about Maxwell's demon. This demon was actually conjured up by the famous James Clerk Maxwell, one of the most innovative physicists of the 19th Century. He is most famous for developing the 4 coupled equations that completely describe the fields of electricity and magnetism. One of the other physics topics he worked on was that of thermodynamics, a subject considered essential at that time to understand how engines and other sources produce work. 3 laws had been developed on thermodynamics years before -- principles that were developed as a result of the enlightenment of the industrial revolution. But Maxwell saw a puzzling problem about the 2nd law of thermodynamics.

The 2nd law of thermodynamics says that if 2 containers side-by-side are in thermal equilibrium with each other, they will stay in thermal equilibrium. But Maxwell postulated that if there was a little demon opening up a small door between the containers, the demon could monitor thermal molecular motion by only allowing fast molecules to pass through into one container, and slow molecules to pass through into the other container. Thus over time the demon would cause the 2 containers to move out of thermal equilibrium with each other, in seeming contradiction to the 2nd law.

The resolution of the paradox formulation by Maxwell is that that little demon must of necessity be considered part of the physical system. To get the extremely large amount of information on the movement of septillions of molecules requires external work, and with that external work considered there is no violation of the 2nd law of thermodynamics. In fact 20th century statistical physics was developed to go beyond thermodyamics, and includes those extremely small remote possibilities (such as all this information being transmitted to septillions of molecules) in analysis of the expected outcome.

In the case of the ostensible collapse of WTC7 initiating by a local buckling from fires that was formulated by NIST, that demon would have to control the flow at millions of such doors along the top of the building to maintain that amazing symmetry for the under-7-second collapse. Fires in general are very asymmetrical, so the demon would have to get the burned structures in the right place at all these points for the catastropic timing of the collapse to produce this amazing symmetry. But if the architectural failure started locally from fires as the NIST Committe claims, that local asymmetry would have to result in a global perfectly-symmetric fall within hundredths of a second. All of the information from the locally asymmetric failure would have to propagate to all corners of the building and almost instaneously create a perfectly symmetric fall. The demon would have to move at an extremely fast rate to these millions of doors to control this amazing transition to global symmetry. The statistical odds of this happening are so overwhelmingly small that the scenario is patently absurd.

But again, moving between millions of doors at extremely fast speeds to obtain this amazing symmetry is not the only feat the demon would have to do. Building 7 of the WTC fell with perfect symmetry and at freefall from its very start. The establishment of freefall came from very careful timing and measurement by David Chandler in 3 videos in a series entitled "WTC7: NIST Finally Admits Freefall" he produced and placed on the web ( www.911speakout.org ). NIST admitted the building was in freefall for more than the first 2 seconds of its collapse, despite claims they made when they first released the WTC7 Report on August 21 that it was not in freefall.

The implications of the fact that the collapse was in freefall are that the gravitational energy was totally used for the freefall of the building. The well-known physics principle of conservation of energy shows that there was no gravitational energy left to break the building apart as it fell. If gravity was the only source of energy, there is no energy to cause the structure to collapse as it falls. Conservation of energy shows this could only happen if the building fell as if it was liquid water, as if all material cohesion within the building had been destroyed when it started falling. Destroying this cohesion would clearly require a separate energy source than gravitation. Freefall of the building shows that the gravitational collapse conjectured in the NIST Report cannot happen!

Thus to attain freefall of the building with perfect symmetry, Maxwell's demon would not only have to move at extremely high speeds between millions of doors to maintain this perfect symmetry, it would also have to violate well-established physics conservation laws. Maxwell's demon might be able to pull off the fantastically improbable, but he cannot perform the impossible.

Maxwell's hypothetical demon would in fact be powerless to violate physics conservation principles. No violation of these conservation principles have ever been found. It would also be extremely unlikely the demon could get the information to millions of points in time to maintain the amazing symmetry of the graceful fall of the building. For the top of Building 7 to fall at the free-fall rate with such graceful symmetry would in fact require substantial amounts of exlosive-type energy to quickly and completely obliterate the full material cohesion and create this very non-resistive state all across the building. In fact, barring explosive energy breaking up the solid material, that lower contiguous material counters falling parts from above, and conservation of energy and momentum keeps the free-fall state from ever being approached. The NIST Committee completely ignored conservation of energy and momentum in all their calculations, not only for Building 7 but also for the Towers, erroneously deducing that the buildings can collapse gravitationally at close to the "free-fall" rate from fires alone.

The calculations were made as follows: a perpendicular line was drawn to connect the leftmost points of the Start and End lines. The point of crossing of this line and the lowest point of the quadrangular "black box" was marked with "A". The distances from A to the Start and End lines are h1=8.1 meters and h2=58.8 meters, respectively. After starting to fall, A used 2.34 seconds to fall the distance between the Start and End lines (50.7 meters). This translates into an acceleration of 8.5 m/s2 and a resistance factor of 13 percent.

World Trade Center 7 was the third skyscraper destroyed on September 11, 2001. It was not hit by a plane. The picture on the left shows WTC 7 after the collapse of the Twin Towers, smoldering in the background.

The final report on its collapse, postponed several times, was published over 7 years after the event on November 20, 2008.

This steel-framed skyscraper, completed in 1987, was located 110 meters (350 feet) away from the closest of the Twin Towers ("WTC 1" on the map below). The building's tenants included the CIA, the Internal Revenue Service, several banks, the Mayor's Office of Emergency Management, and the U.S. Securities & Exchange Commission. A large number of records of ongoing investigations of Enron and other companies were destroyed with WTC 7.

No airplane hit WTC 7, but its south facade was damaged by debris ejected from the North Tower, which collapsed at 10.30 am. There is conflicting information about the amount of damage. For example, in the pictures shown in a preliminary official report the southwest corner is badly damaged, whereas in the photograph taken by Aman Zafar in the afternoon the same corner is intact – see my photo comparison. The building was reported on fire at 4.10 pm by CNN, although the fires seem to have started in the morning after the destruction of the North Tower. The fires, whose origin has not been determined, appeared on a number of floors, and the evacuated building collapsed at 5.20 pm.

A high-resolution video of the collapse is available here. The video below shows the totality and symmetry of the building's destruction.

The Federal Emergency Management Agency, FEMA, speculated that office fires caused the collapse of the building. It, however, acknowledged in its report in May 2002: "The specifics of the fires in WTC 7 and how they caused the building to collapse remain unknown at this time. [...] the best hypothesis has only a low probability of occurrence." Later in 2002, Larry Silverstein, the owner of WTC 7, gave in the America Rebuilds TV program the famous "pull it" statement that many have interpreted as meaning that the building was professionally demolished.

Did WTC 7 collapse as a result of office fires, or was it demolished with explosives? The answer can be sought by examining the way in which the building collapsed.

Collapse Speed

As one can observe from the videos of WTC 7's collapse, after the roofline began its smooth descent, the building fell to the ground in approximately 6.5 seconds. This is a phenomenally short time: a stone dropped from the top of the building would have reached the ground (covering a distance of 174 meters) in 5.95 seconds – if there were no air resistance! However, in principle the distance analyzed should be that from the top of the building to the top of the debris pile, not to the ground. As the exact height of the debris pile is not documented, it is more useful to examine the early stages of the collapse, during which the debris pile does not need to be taken into account.

According to the video analysis presented in the 9-11 Eyewitness documentary, starting from the state of rest, WTC 7 fell 100 meters in 4.5 seconds. This results in an acceleration of 9.8 m/s2, corresponding to a free fall.

To verify this, I examined the fall of a corner of the building in one collapse video using Blaze Media Pro video editing software. The corner fell 56 meters (=the distance between the Start and End lines in the animation below) in 3.47 seconds. This results in an acceleration of 9.3 m/s2, which corresponds to a very low resistance factor of the structural supports: only 5 percent of the force of gravity of the building's falling upper section.

I also measured an acceleration of 8.5 m/s2 for the middle part of the wide facade in the picture, which means that the force of resistance of the structural supports was 13 percent of the force of gravity of the falling upper section (see the calculation in more detail here).My measurements therefore support the conclusion presented in 9-11 Eyewitness that the skyscraper fell virtually unimpeded. The lack of structural resistance seems to be explainable only by the destruction of the structural supports through the use of explosives. WTC 7 dropped rather than collapsed. It came down as if only air had separated the roof of the building from the street below.

WTC 7 fell on average 7 floors per second (47 / 6.5). One second after the onset of the collapse, the speed of descent was almost 10 meters/second; after two seconds, almost 20 meters/second; and at the end, about 60 meters/second (over 200 kilometers/hour). According to the analysis of Frank Legge (Ph.D.), the rate of descent of WTC 7 closely matches the rate of gravitational free fall, which – combined with the uniformity of the descent throughout the breadth and length of the building – is irrefutable evidence of controlled demolition.

Heikki Kurttila, a Finnish Doctor of Engineering and accident researcher, has made detailed calculations about the collapse speed of WTC 7. He concludes that the short collapse time and low structural resistance "strongly suggest controlled demolition". Kurttila notes that an apple dropped from the height of WTC 7's roof would have taken about 0.5 seconds longer to reach the ground than it took the skyscraper to be completely destroyed.

Structural Features of the Collapse

A striking feature in the collapse of WTC 7 is symmetry. The collapse progressed evenly throughout the building, and the debris piled up almost completely within the foundations of the building (see the picture below).

The symmetry of WTC 7's descent means that all of its steel supports – 25 central and 58 peripheral columns – were destroyed almost simultaneously. Any asymmetry in the damage to structures would have led to asymmetrical collapse. By contrast, a symmetrical collapse without the controlled use of explosives would violate the principle of least resistance. Local office fires (typically dying out in about 20 minutes in any given location) and structural damage here and there could not have weakened all the central and peripheral support structures in a way that would have caused all of them to fail at the same moment. The simultaneity of the destruction of support structures throughout the building can, however, be explained by controlled demolition.

A controlled demolition is also suggested by the drop of the center of the skyscraper moments before the surrounding structures started to fall, as well as by the fact that the outer walls were pulled inwards. In a controlled demolition the collapse is caused by first destroying the weight-carrying core of a building, which "pulls" the exterior walls inwards ("implosion"). Although the lowest floor with fires was reportedly the sixth floor, the building seems to have undergone a traditional demolition, beginning from the bottom floor. An emergency worker who witnessed the collapse of WTC 7 was interviewed on 9/11. He described hearing what sounded like a "clap of thunder", followed by what looked like "a shockwave ripping through the building", with windows busting out, and "about a second later the bottom floor caved out and the [rest of] the building followed after that". The videos showing the collapse support his description.

At least one high-resolution video of the collapse of WTC 7 clearly shows one more characteristic of controlled demolition: streamers of dust emerging out of the building.

A Dutch demolition expert Danny Jowenko (right), who owns a demolition company and has been in the business for almost 30 years, concluded in September 2006 that WTC 7 "is controlled demolition. [...] A team of experts did this. This is professional work, without any doubt." A number of other demolition experts agree.

Hugo Bachmann, a Swiss professor emeritus for structural design and construction, said in Tages-Anzeiger: "In my opinion WTC 7 was with great probability brought down by controlled demolition done by experts". In addition, Jörg Schneider, another Swiss Professor emeritus for structural design and construction, interprets the existing videos as indicating that "WTC 7 was with great probability brought down by explosives".

Fire Endurance of Steel

Steel is very fire-resistant material. In tests conducted by Corus Construction in several countries, the fire endurance of steel-framed parking garages was examined by feeding fires with hydrocarbon fuel. Steel beams and pillars heated to a maximum of 360 degrees Celsius, and the breaking of steel was not even close. In Cardington fire endurance tests, modelled on conditions in real buildings, unprotected steel was subjected to temperatures of up to 1100 degrees Celsius (2012 F), but there was no collapse. Similarly, in the fire experiments contracted by the National Institute of Standards and Technology (NIST), testing the pancake collapse theory by modelling the fire exposure of WTC's floor assemblies, there was no collapse. Although NIST ignored the results in its final report, it acknowledged that the results "established that this type of assembly was capable of sustaining a large gravity load, without collapsing, for a substantial period of time relative to the duration of the fires in any given location on September 11th."

In the picture of WTC 7 to the right, the fires are limited to small areas, almost all windows are intact, and no red heat indicative of temperatures capable of softening steel is visible. The situation is largely the same in other photographs taken of the building in late afternoon. In some videos, such as this, a fair amount of smoke can be seen emanating from the southern facade (some of the smoke appears to be rising from WTC 5 and WTC 6 as well as from the remains of the twin towers), and several windows were broken on a few floors in the southern wall. In any case, WTC 5, which was badly damaged by the collapse of the North Tower next to it, burned much more powerfully. However, although this building had weaker support structures than WTC 7, it did not collapse into a debris pile, but remained standing – as did all the other highrises equally close to the Twin Towers, including the Verizon, Deutsche Bank, and U.S. Post Office buildings.

In December 2007, it was acknowledged in the advisory committee meeting of the NIST that the fires in WTC 7 were ordinary office fires and burned out in any given location in 20 minutes. In such a short time, the temperature of fire-protected steel members would have maxed out below 200 degrees Celsius (or ~400 degrees Fahrenheit). Such temperatures have no effect on construction steel.

Characteristics of the Debris

The debris of WTC 7 was extremely hot for weeks after the collapse of the building. Thermal imaging by NASA showed that the top of the debris pile had a temperature of 730 degrees Celsius five days after the collapse. Deeper, and immediately after the destruction, temperatures were probably considerably higher. Residual temperatures like this cannot be explained by office fires or by an ordinary, gravity-driven collapse. When the potential energy of a building experiencing an ordinary gravitational collapse turns into thermal energy, the result is only a few degrees' average increase in temperature.

According to several reports, molten metal (also suggested by this video footage) was found under the debris pile of WTC buildings. To melt structural steel, temperatures exceeding 1500 degrees Celsius are required. Such temperatures are never achieved in office fires. In addition to molten metal, partly evaporated steel beams were found in the debris of WTC 7. As professor Jonathan Barnett pointed out in a New York Times interview, the fires in the building could not have produced temperatures capable of evaporating steel. However, the use of explosives like thermite can produce temperatures (even 3000 degrees Celsius) that can melt and even evaporate steel.

FEMA's investigators were not allowed to work in the collapse zone itself. They were allowed to examine the debris of WTC skyscrapers only in landfill areas used as temporary storage for the steel debris before its recycling. By May 2002, when FEMA finished its preliminary report calling for further investigation, almost all the steel debris had been sold and shipped into the Far East. Only 236 pieces of steel had been retained for examination, of which a ridiculous total of 4 were from WTC 7. Even these may no longer exist.

As WTC 7 was evacuated over six hours before its destruction, there were no grounds for the rapid removal and recycling of the steel debris. Quite the contrary: as WTC 7 was one of the three greatest building disasters in recorded history (the other two being the North and South Towers), the debris of the building should have been meticulously examined. Many individuals and publications, such as the Fire Engineering Magazine, protested strongly, but in vain, against the rapid destruction of the evidence.

Witness statements

Craig Bartmer, a NYPD officer, states that he saw WTC 7 come down and heard a number of explosions in rapid succession. He is convinced that the skyscraper was brought down with explosives.

Barry Jennings, the deputy director of the Emergency Services Department of the New York City Housing Authority, has given a detailed statement of explosions in the evacuated WTC 7. As a result of a major explosion on the sixth floor, he and his colleague were trapped inside the building for about an hour and a half before the firemen were able to help them out. The colleague was Michael Hess, New York City’s corporation counsel, who confirmed to UPN 9 News that morning that an explosion in WTC 7 had trapped him and Jennings inside. Jennings emphasized that after the explosion, both of the twin towers were still standing, a statement that is supported by the time of Hess' interview in the morning. The men's statements, combined with the time of Hess' interview, place the explosion around 9:15–9:30, when the two were descending the stairs from the Mayor's Emergency Management Centre on the 23d floor, to which they had gone before the second plane struck the South Tower, only to find the center deserted.

Several rescue personnel have also come forward saying they were told that the building would be brought down by means of explosives. One such statement can be heard in this excerpt of Italian TV's documentary, in which one can also hear explosions from WTC 7: in one scene, a loud explosion is shown startling first responders, while a police officer says "the building is about to blow up".

Final Words

Was WTC 7 destroyed as a result of controlled demolition? Everyone can draw their own conclusions from the way in which the building was destroyed and the temperatures produced in the destruction.

If and when the building was demolished, it must have been wired with explosives before September 11th. An operation of that magnitude could not have been accomplished during a couple of chaotic hours. This is why the official hypotheses have not touched on the most obvious explanation for the collapse of the skyscraper. It is revealing that the 9/11 Commission, which published its report in 2004, does not mention in a single sentence the destruction of the third skyscraper resulting from the terrorist attack in New York.

FEMA's work was continued by the National Institute of Standards and Technology, which finally published its report on WTC 7 on November 20, 2008. NIST claims that thermal expansion resulting from ordinary office fires (not diesel fires) initiated a catastrophic chain of events leading to the total collapse of the skyscraper. The draft report was greeted with widespread disbelief and criticism on the part of both the general public and many experts. A group of architects, engineers and scientists refute NIST's conclusions point by point. The creator of this blog also approached NIST with his own comments.

Perhaps NIST's report needs to be analyzed in the light of how Dr S. Shyam Sunder, NIST's lead WTC investigator, interviewed in New York Magazine, summed up the state of the investigation back in 2006:

NIST did have "some preliminary hypotheses" on 7 WTC, Dr. Sunder said. "We are studying the horizontal movement east to west, internal to the structure, on the fifth to seventh floors." Then Dr. Sunder paused. "But truthfully, I don't really know. We've had trouble getting a handle on Building No. 7."

Important news (see the article for more details):- NIST published its final report in November 2008- NIST acknowledged: fires burned out in 20 minutes in any given location- several demolition experts and structural design professors: WTC 7 was a controlled demolition- Frank Legge (Ph.D.): the rate of descent of WTC 7 almost equals gravitational free fall- Several witnesses to explosions have come forward- Over 2,300 architects and engineers challenge the official explanations for WTC destruction

World Trade Center 7 was the third skyscraper destroyed on September 11, 2001. It was not hit by a plane. The picture on the left shows WTC 7 after the collapse of the Twin Towers, smoldering in the background.

The final report on its collapse, postponed several times, was published over 7 years after the event on November 20, 2008.

This steel-framed skyscraper, completed in 1987, was located 110 meters (350 feet) away from the closest of the Twin Towers ("WTC 1" on the map below). The building's tenants included the CIA, the Internal Revenue Service, several banks, the Mayor's Office of Emergency Management, and the U.S. Securities & Exchange Commission. A large number of records of ongoing investigations of Enron and other companies were destroyed with WTC 7.

No airplane hit WTC 7, but its south facade was damaged by debris ejected from the North Tower, which collapsed at 10.30 am. There is conflicting information about the amount of damage. For example, in the pictures shown in a preliminary official report the southwest corner is badly damaged, whereas in the photograph taken by Aman Zafar in the afternoon the same corner is intact – see my photo comparison. The building was reported on fire at 4.10 pm by CNN, although the fires seem to have started in the morning after the destruction of the North Tower. The fires, whose origin has not been determined, appeared on a number of floors, and the evacuated building collapsed at 5.20 pm.

A high-resolution video of the collapse is available here. The video below shows the totality and symmetry of the building's destruction.

The Federal Emergency Management Agency, FEMA, speculated that office fires caused the collapse of the building. It, however, acknowledged in its report in May 2002: "The specifics of the fires in WTC 7 and how they caused the building to collapse remain unknown at this time. [...] the best hypothesis has only a low probability of occurrence." Later in 2002, Larry Silverstein, the owner of WTC 7, gave in the America Rebuilds TV program the famous "pull it" statement that many have interpreted as meaning that the building was professionally demolished.

Did WTC 7 collapse as a result of office fires, or was it demolished with explosives? The answer can be sought by examining the way in which the building collapsed.

Collapse Speed

As one can observe from the videos of WTC 7's collapse, after the roofline began its smooth descent, the building fell to the ground in approximately 6.5 seconds. This is a phenomenally short time: a stone dropped from the top of the building would have reached the ground (covering a distance of 174 meters) in 5.95 seconds – if there were no air resistance! However, in principle the distance analyzed should be that from the top of the building to the top of the debris pile, not to the ground. As the exact height of the debris pile is not documented, it is more useful to examine the early stages of the collapse, during which the debris pile does not need to be taken into account.

According to the video analysis presented in the 9-11 Eyewitness documentary, starting from the state of rest, WTC 7 fell 100 meters in 4.5 seconds. This results in an acceleration of 9.8 m/s2, corresponding to a free fall.

To verify this, I examined the fall of a corner of the building in one collapse video using Blaze Media Pro video editing software. The corner fell 56 meters (=the distance between the Start and End lines in the animation below) in 3.47 seconds. This results in an acceleration of 9.3 m/s2, which corresponds to a very low resistance factor of the structural supports: only 5 percent of the force of gravity of the building's falling upper section.

I also measured an acceleration of 8.5 m/s2 for the middle part of the wide facade in the picture, which means that the force of resistance of the structural supports was 13 percent of the force of gravity of the falling upper section (see the calculation in more detail here).My measurements therefore support the conclusion presented in 9-11 Eyewitness that the skyscraper fell virtually unimpeded. The lack of structural resistance seems to be explainable only by the destruction of the structural supports through the use of explosives. WTC 7 dropped rather than collapsed. It came down as if only air had separated the roof of the building from the street below.
WTC 7 fell on average 7 floors per second (47 / 6.5). One second after the onset of the collapse, the speed of descent was almost 10 meters/second; after two seconds, almost 20 meters/second; and at the end, about 60 meters/second (over 200 kilometers/hour). According to the analysis of Frank Legge (Ph.D.), the rate of descent of WTC 7 closely matches the rate of gravitational free fall, which – combined with the uniformity of the descent throughout the breadth and length of the building – is irrefutable evidence of controlled demolition.

Heikki Kurttila, a Finnish Doctor of Engineering and accident researcher, has made detailed calculations about the collapse speed of WTC 7. He concludes that the short collapse time and low structural resistance "strongly suggest controlled demolition". Kurttila notes that an apple dropped from the height of WTC 7's roof would have taken about 0.5 seconds longer to reach the ground than it took the skyscraper to be completely destroyed.

Structural Features of the Collapse

A striking feature in the collapse of WTC 7 is symmetry. The collapse progressed evenly throughout the building, and the debris piled up almost completely within the foundations of the building (see the picture below).

The symmetry of WTC 7's descent means that all of its steel supports – 25 central and 58 peripheral columns – were destroyed almost simultaneously. Any asymmetry in the damage to structures would have led to asymmetrical collapse. By contrast, a symmetrical collapse without the controlled use of explosives would violate the principle of least resistance. Local office fires (typically dying out in about 20 minutes in any given location) and structural damage here and there could not have weakened all the central and peripheral support structures in a way that would have caused all of them to fail at the same moment. The simultaneity of the destruction of support structures throughout the building can, however, be explained by controlled demolition.

A controlled demolition is also suggested by the drop of the center of the skyscraper moments before the surrounding structures started to fall, as well as by the fact that the outer walls were pulled inwards. In a controlled demolition the collapse is caused by first destroying the weight-carrying core of a building, which "pulls" the exterior walls inwards ("implosion"). Although the lowest floor with fires was reportedly the sixth floor, the building seems to have undergone a traditional demolition, beginning from the bottom floor. An emergency worker who witnessed the collapse of WTC 7 was interviewed on 9/11. He described hearing what sounded like a "clap of thunder", followed by what looked like "a shockwave ripping through the building", with windows busting out, and "about a second later the bottom floor caved out and the [rest of] the building followed after that". The videos showing the collapse support his description.

At least one high-resolution video of the collapse of WTC 7 clearly shows one more characteristic of controlled demolition: streamers of dust emerging out of the building.
A Dutch demolition expert Danny Jowenko (right), who owns a demolition company and has been in the business for almost 30 years, concluded in September 2006 that WTC 7 "is controlled demolition. [...] A team of experts did this. This is professional work, without any doubt." A number of other demolition experts agree.

Hugo Bachmann, a Swiss professor emeritus for structural design and construction, said in Tages-Anzeiger: "In my opinion WTC 7 was with great probability brought down by controlled demolition done by experts". In addition, Jörg Schneider, another Swiss Professor emeritus for structural design and construction, interprets the existing videos as indicating that "WTC 7 was with great probability brought down by explosives".

Fire Endurance of Steel

Steel is very fire-resistant material. In tests conducted by Corus Construction in several countries, the fire endurance of steel-framed parking garages was examined by feeding fires with hydrocarbon fuel. Steel beams and pillars heated to a maximum of 360 degrees Celsius, and the breaking of steel was not even close. In Cardington fire endurance tests, modelled on conditions in real buildings, unprotected steel was subjected to temperatures of up to 1100 degrees Celsius (2012 F), but there was no collapse.

Similarly, in the fire experiments contracted by the National Institute of Standards and Technology (NIST), testing the pancake collapse theory by modelling the fire exposure of WTC's floor assemblies, there was no collapse. Although NIST ignored the results in its final report, it acknowledged that the results "established that this type of assembly was capable of sustaining a large gravity load, without collapsing, for a substantial period of time relative to the duration of the fires in any given location on September 11th."

In the picture of WTC 7 to the right, the fires are limited to small areas, almost all windows are intact, and no red heat indicative of temperatures capable of softening steel is visible. The situation is largely the same in other photographs taken of the building in late afternoon. In some videos, such as this, a fair amount of smoke can be seen emanating from the southern facade (some of the smoke appears to be rising from WTC 5 and WTC 6 as well as from the remains of the twin towers), and several windows were broken on a few floors in the southern wall. In any case, WTC 5, which was badly damaged by the collapse of the North Tower next to it, burned much more powerfully. However, although this building had weaker support structures than WTC 7, it did not collapse into a debris pile, but remained standing – as did all the other highrises equally close to the Twin Towers, including the Verizon, Deutsche Bank, and U.S. Post Office buildings.

In December 2007, it was acknowledged in the advisory committee meeting of the NIST that the fires in WTC 7 were ordinary office fires and burned out in any given location in 20 minutes. In such a short time, the temperature of fire-protected steel members would have maxed out below 200 degrees Celsius (or ~400 degrees Fahrenheit). Such temperatures have no effect on construction steel.Characteristics of the Debris

The debris of WTC 7 was extremely hot for weeks after the collapse of the building. Thermal imaging by NASA showed that the top of the debris pile had a temperature of 730 degrees Celsius five days after the collapse. Deeper, and immediately after the destruction, temperatures were probably considerably higher. Residual temperatures like this cannot be explained by office fires or by an ordinary, gravity-driven collapse. When the potential energy of a building experiencing an ordinary gravitational collapse turns into thermal energy, the result is only a few degrees' average increase in temperature.

According to several reports, molten metal (also suggested by this video footage) was found under the debris pile of WTC buildings. To melt structural steel, temperatures exceeding 1500 degrees Celsius are required. Such temperatures are never achieved in office fires. In addition to molten metal, partly evaporated steel beams were found in the debris of WTC 7. As professor Jonathan Barnett pointed out in a New York Times interview, the fires in the building could not have produced temperatures capable of evaporating steel. However, the use of explosives like thermite can produce temperatures (even 3000 degrees Celsius) that can melt and even evaporate steel.

FEMA's investigators were not allowed to work in the collapse zone itself. They were allowed to examine the debris of WTC skyscrapers only in landfill areas used as temporary storage for the steel debris before its recycling. By May 2002, when FEMA finished its preliminary report calling for further investigation, almost all the steel debris had been sold and shipped into the Far East. Only 236 pieces of steel had been retained for examination, of which a ridiculous total of 4 were from WTC 7. Even these may no longer exist.
As WTC 7 was evacuated over six hours before its destruction, there were no grounds for the rapid removal and recycling of the steel debris. Quite the contrary: as WTC 7 was one of the three greatest building disasters in recorded history (the other two being the North and South Towers), the debris of the building should have been meticulously examined. Many individuals and publications, such as the Fire Engineering Magazine, protested strongly, but in vain, against the rapid destruction of the evidence.

Witness statements
Craig Bartmer, a NYPD officer, states that he saw WTC 7 come down and heard a number of explosions in rapid succession. He is convinced that the skyscraper was brought down with explosives.

Barry Jennings, the deputy director of the Emergency Services Department of the New York City Housing Authority, has given a detailed statement of explosions in the evacuated WTC 7. As a result of a major explosion on the sixth floor, he and his colleague were trapped inside the building for about an hour and a half before the firemen were able to help them out. The colleague was Michael Hess, New York City’s corporation counsel, who confirmed to UPN 9 News that morning that an explosion in WTC 7 had trapped him and Jennings inside. Jennings emphasized that after the explosion, both of the twin towers were still standing, a statement that is supported by the time of Hess' interview in the morning.

The men's statements, combined with the time of Hess' interview, place the explosion around 9:15–9:30, when the two were descending the stairs from the Mayor's Emergency Management Centre on the 23d floor, to which they had gone before the second plane struck the South Tower, only to find the center deserted.

Several rescue personnel have also come forward saying they were told that the building would be brought down by means of explosives. One such statement can be heard in this excerpt of Italian TV's documentary, in which one can also hear explosions from WTC 7: in one scene, a loud explosion is shown startling first responders, while a police officer says "the building is about to blow up".

Final Words

Was WTC 7 destroyed as a result of controlled demolition? Everyone can draw their own conclusions from the way in which the building was destroyed and the temperatures produced in the destruction.
If and when the building was demolished, it must have been wired with explosives before September 11th. An operation of that magnitude could not have been accomplished during a couple of chaotic hours. This is why the official hypotheses have not touched on the most obvious explanation for the collapse of the skyscraper. It is revealing that the 9/11 Commission, which published its report in 2004, does not mention in a single sentence the destruction of the third skyscraper resulting from the terrorist attack in New York.FEMA's work was continued by the National Institute of Standards and Technology, which finally published its report on WTC 7 for public comment on November 20, 2008. NIST claims that thermal expansion resulting from ordinary office fires (not diesel fires) initiated a catastrophic chain of events leading to the total collapse of the skyscraper. The draft report was greeted with widespread disbelief and criticism on the part of both the general public and many experts. A group of architects, engineers and scientists refute NIST's conclusions point by point. The creator of this blog also approached NIST with his own comments.

Perhaps NIST's report needs to be analyzed in the light of how Dr S. Shyam Sunder, NIST's lead WTC investigator, interviewed in New York Magazine, summed up the state of the investigation back in 2006:NIST did have "some preliminary hypotheses" on 7 WTC, Dr. Sunder said. "We are studying the horizontal movement east to west, internal to the structure, on the fifth to seventh floors." Then Dr. Sunder paused. "But truthfully, I don't really know. We've had trouble getting a handle on Building No. 7."